Network-based computing models have been gaining popularity in recent years as cost effective approaches to managing enterprise computing needs. Ranging from network-managed PCs, network computers, thin-clients, to server-centric clients, network-based computing is largely motivated by the need to reduce the cost of providing IT services (known as the Total Cost of Ownership, TCO) in networked computing environments. It is well known in the industry that the most expensive part of providing computing resources to end-users is not the cost of the computing hardware and software but the cost of on-going maintenance and management. See, Thin Client Benefits, Newburn Consulting (2002); Total Cost of Application Ownership, The Tolly Group Whitepaper (1999); TCO Analyst: A White Paper on GartnerGroup's Next Generation Total Cost of Ownership Methodology, GartnerConsulting (1997). According to these well known studies, network-based computing models can significantly reduce the TCO by centralizing the maintenance and management functions of IT services, thereby reducing the recurring cost of on-going maintenance and management.